List of symptoms

Most infected people don't have symptoms from West Nile virus or St. Louis encephalitis. Those most at risk for serious neurological illness from the sometimes fatal diseases are the elderly and very young, pregnant women and people with compromised immune systems.

Fight the bite

• Use repellents with DEET, picaridin, IR3535, oil of lemon eucalyptus or para-menthane-diol.

• If using sunscreen, apply sunscreen, then bug repellent.

• Prevent breeding sites by removing standing water and all outdoor potential water containers, even bottle caps and tin cans.

• Keep screens repaired.

• Remove standing water or get help from a mosquito abatement program.

• Use mosquito fish, free from vector control programs, for livestock troughs, ponds or lakes.

• Report mosquito bites, especially during the day, to local vector control.

• Report dead birds to local vector control or the state online at www.westnile.ca.gov or by calling 1-877-968-2473.

Disease control officials fear high numbers of Californians could be infected with mosquito-borne West Nile virus for the third straight year after activity has spiked in Los Angeles, Orange and San Diego counties and the Central Valley.

While Riverside and San Bernardino counties have escaped similar increases so far, the Inland region is facing a renewed threat from St. Louis encephalitis after the disease was found in both counties following long absences.

The agencies also are stepping up efforts to kill the mosquitoes that spread West Nile after the numbers of infected dead birds, mosquitoes and sentinel chickens are rising higher than this time last year in parts of Southern California and the Central Valley.

“There is the potential for many more West Nile human cases this year,” said Dr. Vicki Kramer, chief of the California Department of Public Health’s Vector-Borne Disease Section.

Most infected people have no symptoms, which can include fever, headache, body aches, joint pains, vomiting, diarrhea or rash. Those most at risk for serious neurological illness from the virus are the elderly and very young, pregnant women and people with compromised immune systems.

On Aug. 5, State Health Officer Dr. Karen Smith reported California’s first death from the disease this year. An elderly person died recently in Sacramento County, which leads the state with 344 dead birds and 340 mosquito samples found with West Nile. Samples usually range from 10 to 50 mosquitoes, but some programs, like San Bernardino County’s, will turn in even one insect.

The number of people infected with West Nile statewide was 10 as of Aug. 5 – roughly half the 22 people who were found with the disease this time last year.

However, the number of dead wild birds sent in to the state – 834 – has more than doubled since the same time in 2015. And nearly 510 more infected mosquito sampleswere turned in statewide compared to early August last year.

This year’s elevated activity comes after California was hit with a record 53 West Nile deaths in 2015 – a number that dwarfed such deaths in every other state last year and far surpassed those reported in California in any previous year.

The 860 Californians infected with West Nile last year also outpaced the disease’s impact elsewhere in the country.

Riverside and San Bernardino counties are seeing lower numbers of infected birds and mosquitoes so far. That’s a good sign, said San Bernardino County Environmental Health Services Mosquito and Vector Control Program Manager Jason Phillippe, adding the county hasn’t found any infected dead birds this year.

“But of course, we want people to remain vigilant because that could change at any time. We don’t want people to let their guard down,” Phillippe said.

Orange County and especially Los Angeles County have significantly more infected birds and mosquitoes than last year. Los Angeles County also has far more infected sentinel chickens.

Greater Los Angeles County Vector Control District officials are concerned at the activity level. Spokesman Levy Sun said that’s because the risk of people getting sick from West Nile is at a near-five-year high.

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